fix(frontend): change search icon on menu (#2043)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/lib/components/Menu/components/DiscussionButton.tsx

@@ -1,7 +1,7 @@
 import Link from "next/link";
 import { usePathname } from "next/navigation";
 import { useTranslation } from "react-i18next";
-import { LuChevronRight, LuMessageSquare } from "react-icons/lu";
+import { LuChevronRight, LuSearch } from "react-icons/lu";
 
 import { Button } from "@/app/chat/[chatId]/components/ActionsBar/components/ChatInput/components/ActionsModal/components/Button";
 import { cn } from "@/lib/utils";
@@ -15,7 +15,7 @@ export const DiscussionButton = (): JSX.Element => {
     <Link href="/search">
       <Button
         label={t("search")}
-        startIcon={<LuMessageSquare />}
+        startIcon={<LuSearch />}
         endIcon={<LuChevronRight size={18} />}
         className={cn(
           "w-full hover:bg-secondary py-3",